My Sister is a Dickgirl

My Sister is a Dickgirl is yet another piece of fine literature that only the internet could produce, and then quickly took the net by storm. Similar to Usenet classic Raping Little Suzy, the core theme of the work revolves around mindless sex with one's family (although RLS is far more graphic). Following the misadventures of the hormone crazed protagonist and his sister plus oneCassie, My Sister is a Dickgirl has survived years of relentless reposts, ultimately being one of the most widespread copypastas of all time.

“Knock it off already.” Cassie had the remote control firmly entrenched in her hand and was doing her best to keep it out of reach. The TV was stuck on basketball, which sucked. I knew that there had to be some combination of leverage and brute force that would cause my sister’s fingers to open and let me gain command of the remote. Getting up and walking to the TV was simply out of the question.

“Knock what off?,” I replied, making another grab. Cassie just rolled her eyes and pushed me away. Time for a desperation move. I stuck my thumb in my mouth just long enough to let it collect a good amount of spit, then, distracting her with another lunge for the remote, I slid my thumb past her defenses and rubbed it over her left ear.

“Ewww! Fucking gross!” Her grip loosened just enough for me to pry the device from her hand. My victory was sweet, but it was also short.

“Okay, Knob. You asked for it.” She grabbed me by the wrist and deftly twisted it behind my back, using her three-year age lead and height advantage to throw me down on the couch. She pinned me on my stomach and quickly moved into a sitting position on my shoulders, resting her full weight down on me to keep me from escaping. It was pretty much over. I knew what was coming next, and with one final effort I raised my free hand and succeeded in changing the channel before she could wrestle the remote away. Yes! No matter what happened now, she could never take that away from me.

I closed my eyes as I heard her unzip her pants. My embarrassment was unreal as she began whacking me on the back of the head with a blunt, meaty object.

As a boy, it’s not easy growing up with a sister who has a bigger penis than you do.

My family isn’t exactly normal. Cassie’s dad was killed in car crash when she was only a year old. Mom got married again and had me, but my dad ran off with a car show model when I was seven, leaving my mom to take care of us by herself. We’ve been though some rough times, but I think we’re closer because of it. And also weirder.

My sister Cassie is…well, different. When Cassie was born she was what they call ‘intersexed,’ which is the name for what happens when your parts are mixed up between being male and female. They decided to operate and make her into a boy, but as she got older it started to be obvious that she wasn’t supposed to be one. Now at sixteen you couldn’t guess that she was anything other than a slighty tomboyish teenage girl. She looked like a girl, dressed like a girl, and even smelled like a girl. She pretty much *was* a girl in every way except for what she had between her legs. A lot of people seem to think that’s the only place that counts, but living with Cassie has taught me that its what’s in your head that really matters.

It was a little strange growing up with her, but I pretty much got used to the fact that she had a ‘thingy’ like I did. The strangeness increased when she hit puberty and started growing boobs, something that the doctors said was unusual since she hadn’t been taking hormones. They gave her some to try out and her boobs got even bigger. Her hips got wider too and she started getting taller. I was still pretty small for my age and it soon became clear that she could beat me up pretty easily. Not that she ever really did, but anytime we had a wrestling match she would win pretty easily. We usually got along well, but as we both got older things started to get…complicated.

Our mom was working long shifts at the hospital, leaving Cassie in charge at home. I didn’t enjoy being bossed around by my sister, so sometimes I got pretty rebellious. Then Cassie developed her unique way of dealing with me, and I quickly learned that making her mad was a bad idea. That didn’t always stop me, however.

Sometimes she got really irritable. She didn’t seem to have many friends even though she was smart and wasn’t bad looking. She liked guys and even had a boyfriend for a while when she was fourteen, but he’d peeked at her once when she was changing in his parent’s poolhouse and totally freaked out. He broke up with her right after that and she’d hadn’t had a boyfriend since. She was probably pretty lonely. Sometimes I felt sorry for her, but she could also be a real pain to live with.

She was in one of those moods one night when I suddenly got a hyperactive urge to tempt fate. I crept up behind her as she was laying sidelong on the couch. She was watching basketball again. I waited until one of the players made a three-pointer, then I reached down with lightning speed and snapped her bra as hard as I could.

“He shoots, he scores!” I yelled, then ran for my life. It was the typical kind of foolishly suicidal thing you do when you’re thirteen and bored out of your mind.

She snarled and lunged, but I was already sprinting back upstairs, hoping that I could barricade myself in my room before she caught up. I almost made it. She shoved the door open with her shoulder before I could get it completely closed and jumped on me.

This time I knew I was in trouble. The look on my big sister's face made it clear that I was dead meat. I wasn’t going to give up without a fight though. We crashed onto the bed and wrestled like mad, grunting and growling like a couple of crazy animals. It lasted a few minutes before she distracted me with a charley horse and pinned me to the mattress. We were both panting for breath and I was suddenly very aware of her boobs pressing against my back as she held me down. It was a good thing I was on my stomach. The grappling match had left me with a painfully stiff hard-on, embarassing but not terribly unusual. A gentle breeze could often make me hard those days. Acting tired, I relaxed and pretended to give up. I planned on trying to throw her off when she moved up to administer the standard thwacking, but she stayed laying on top of me and didn’t move. Afraid that she was thinking up some new and even worse punishment, I quickly flipped myself over on the bed and almost succeeded at knocking her to the floor. She squealed and shoved me back down, hopping up to sit on my chest with her thighs locked around my head. Her leg had brushed against my crotch as she moved up, and to my surprise she suddenly reached back and grabbed my dick through my pants.

“I thought I felt a little pin-prick,’ she said, grinning evilly down at me.

“Shut up,” was my witty comeback.

“Make me.”

I struggled to push her off but her knees had a deathgrip on my head, squeezing down around it like a nutcracker. Still grinning, she reached down and started unbuttoning her fly.

“I think you need to see what a real one looks like,” she said, her voice quieter but no less malevolent. I winced, afraid to look as she pulled out her cock.

his was *soooo* not right. I could already imagine the many years of therapy that were lying in wait for me. Still, I couldn’t help but look. She had some trouble getting it out, and when she finally succeeded it was obvious why. She was just as hard as I was. Seeing a rigid PENIS sticking out from the fly of a teenage girl sitting on your chest is an experience that’s not easy to describe, especially when that girl is your sister and you realize that her dick is bigger than your own. I found myself staring up at it in in a state of mild shock. It wasn’t bad as far as penises go I guess; it was maybe five inches long and looked really smooth and clean. It was also, though I hate to admit it, almost *cute.*

She pinned my hands to the bed and looked down at me with a wicked gleam in her eyes. Her cheeks were turning a hot red color like she was blushing. I expected her to slap me with it or something, but she just sat there with her dick pointing slightly down at my face. My heart was hammering in my chest, and I suddenly realized that I was getting really turned on. There were so many things wrong here that it was hard to keep track. And it was about to get even worse.

Cassie’s grin had faded, replaced with an expression of…I wasn’t sure what. Her face was suddenly serious and her boobs were rising and falling with her breathing. Her cock hung stiffly only a few inches away, aiming almost direcly for my mouth. “Suck it,” she said quietly, almost in a whisper.

I stared at her dick for a moment, not sure exactly what I wanted to do. I’d never even thought about trying something like this before, but...

Without even fully realizing I was doing it, I lifted my head up and gave her cock a little lick. It smelled like the body wash she used and didn’t really taste like anything. Not bad so far. I took the head between my lips and gave it a few experimental sucks. It felt warm and very stiff. Cassie gasped and leaned down over me, pushing herself further into my mouth. I started sucking harder and took as much as I could, feeling it twitch every time the head nudged against my throat. I wasn’t sure if I was doing it right, but the way she was gasping and panting led me to believe that she liked it. She was gripping my hands so tight it almost hurt. Suddenly her whole body tensed up, and before I knew what was happening there was a sudden gush of warm, salty liquid in my mouth. She let out a low groan as her cock jumped again, pumping out more of her stuff. It tasted kinda gross. I guess I could have pulled my head away, but I think I was too stunned to move. For some reason I hadn’t expected her to cum the same way a boy did.

After a few more squirts, Cassie’s body relaxed and she slowly rolled off me. She sat at the edge of the bed and looked at me for a second, then suddenly stood up and ran out of the room. Not sure what else to do, I went to the bathroom to spit the stuff out. I rinsed my mouth, feeling ashamed as I realized I was still hard as a rock. It was all very confusing. Did this mean I was gay? I walked to Cassie’s room and stopped outside the door. I could hear the sound of quiet sobbing from inside. I didn’t know what I should do. I wasn’t even sure why she was crying. The situation was just too fucking weird. I went back to my room to fire up my Xbox and tried to forget about it for a while.

Cassie avoided me for almost a week. I didn’t know if she was disgusted with me or just ashamed of what had happened. I wasn’t sure how I felt about it, but I knew that I didn’t want things to stay weird between us forever. That weekend I waited until mom had gone to bed and then went down the hall to Cassie’s room. I could see a faint light coming from underneath the door so I knew she was probably awake. I knocked softly.

“Cassie?”

There was a moment of silence. “Yeah?”

“Can I come in?”

Another pause, but shorter this time. “Okay.”

I went in and closed the door behind me. Cassie was sitting on the edge of the bed wearing only a bra and a pair of boxers. It looked like she’d been reading a book. My eyes immediately locked on her boobs. They were pretty big and were pushing out of the top of her bra like she was starting to outgrow it. I forced myself to look up at her eyes, but she wasn’t looking at me. Neither of us said anything for a few moments.

“Uh, I just wanted to say I’m sorry for, um…” I trailed off, not sure how I should finish. There wasn’t exactly a Hallmark message for this kind of thing.

Cassie finally looked up at me, looking shocked. “*You’re* sorry? Jesus.” She got up and gave me an awkward hug. It was my turn to feel a bit surprised. She hadn’t hugged me in years. I’d been more expecting her to scream and maybe throw something. I could feel her boobs pushing firmly against my chest, and it was starting to have an effect on me. My shorts suddenly felt much tighter.

“It wasn’t your fault. I made you do it.” She said, her head resting lightly on my shoulder. “Do you hate me?”

“No.” I didn’t. In fact, hugging her like this was making me feel warm and lightheaded.

“Good.” She pulled away with a smile, but her smile quickly faded as she looked down and noticed my hard-on though my shorts.

“God, you are such a perv.” She punched me on the chest and walked back to her bed.

“Yeah, well, so are you.” I said, then as she turned back to glare at me I quickly lunged in and yanked her boxers down around her knees. Cassie shrieked and tried to hide herself as she reached to pull them up. I was still able to get a pretty good look. She didn’t have much hair on her crotch. Her PENIS was semi-hard and I could see that she had a small set of balls hanging down below it. It was pretty weird seeing a package on the body of a sixteen year old girl, but I was starting to get used to weird things.

“You are *so* dead!” She growled.

I decided to make a pre-emptive strike while she was still dealing with her underwear. I tackled her backwards onto the bed, managing to gain the upper hand as she kicked and growled at me. After a quick but frenzied struggle I was able to flip her onto her stomach and pin her hands.

Resting my weight on top of her, I started wondering what I could do to embarrass her and pay her back a little. The fact that I’d managed to pin her on her own bed while she was half-naked was probably pretty humiliating by itself. I wasn’t in much of a hurry to decide. Rare victories like this needed to be savored. Also, her butt was rubbing against me as she tried to push me off, and it felt kinda good.

“Let go!” She twisted underneath me and I felt my dick slip between the cheeks of her ass. It lay trapped between us, pointed up at the small of her back.

Sometimes I called her ‘Assie’ because her rear end was kinda big, but mostly just because the name pissed her off. Right now though it was nothing to joke about. Her boxers were only covering her ass halfway and the warmth and softness of her butt was feeling really good even through my shorts. I had an idea that I shouldn’t be doing this…it seemed almost like rape. It was the only position I could keep her down in though, and I knew that the second I let up she would kill me.

Just then I noticed that she’d mostly stopped struggling. She was still twisting around a little but it didn’t seem like she was trying very hard to knock me off. Mostly it was just making my dick rub against her ass even more. After a few moments it dawned on me that she might be doing it on purpose. I’m normally a bit quicker on the uptake, but the idea that Cassie could somehow *want* me to dry hump her butt just seemed crazy.

Crazy or not, it was starting to feel pretty damn nice. I decided to risk seeing if I could make it even better. She didn’t move as I let one of her hands go and worked my shorts open. I pulled her boxers down a little more, then moved back into place with my dick laying on her naked butt. I noticed quickly that the feel of skin on skin was much, much better. I moved my hips a little so that my cock rubbed slowly back and forth on the crack of her ass. I didn’t know if this was what actual sex was like, but it felt awesome.

I got so lost in the sensations of pushing against her butt that I didn’t realize I was about to cum until it was already happening. I couldn’t move, or even think as my stuff started launching out all over her back. I’d played with myself plenty of times, but this was the most intense cum I’d ever had. I moved off of her when it finally stopped, suddenly feeling ashamed of myself. Cassie’s back and shoulders were streaked and messy with my sperm. Not seeing anything else to clean up with, I used my shorts to mop it up. She was still laying there quietly like she had been the whole time. The only way I knew she was even alive was from her steady breathing.

I sat back on the bed, unable to keep from staring at her butt. There was just something about the curves of her hips and ass that was really hot. If I hadn’t already known she was ‘different,’ there would have been no way to tell from this angle. Acting on a sudden urge, I reached over and gently squeezed her ass with both hands. I kinda expected her to yell at me, but all I heard was something that sounded like a quiet moan. Wondering how far she would let me explore, I slowly pushed her cheeks apart until I could see her little pink butthole. It looked clean and was glistening slightly with sweat. Feeling strangely drawn to it, I moved my hand down and rubbed it lightly with my thumb. She gasped and I felt her jump a little, but she didn’t say anything or push me away. I rubbed it again, then took my hand away and stood up. Maybe she liked me touching her butt, but I had no idea what I was supposed to do down there.

Cassie rolled over on her back and looked at me. Her dick was very stiff and lying back against her stomach, the tip all shiny and wet-looking. I could see the shapes of her nipples poking against her bra. She just laid there watching me as I sat down next to her and put my hand around her cock.

A few days later she came home looking upset. I’d been planning to mess with her again and see what happened, but one look at her face told me that it’d be a bad idea. She stormed past me up to her room and slammed the door behind her. A little while later I was distracted from the TV by a crashing sound from upstairs. It sounded like Cassie was screaming and throwing things. She’d thrown hissy fits before sometimes, but this one sounded bad.

I wondered what was wrong but I knew better than to bother her then. She would probably just try to bounce a lamp off my head or something. I waited until the noise quieted down, then climbed the stairs and went to her room. I couldn’t hear anything on the other side of the door. I knocked. No answer. I knocked harder.

“Go away,” she answered. Her voice sounded faint and shaky.

Never one to obey orders, I slowly opened the door. Her room was a mess and the mirror over her dresser was busted. I started to worry that she’d hurt herself. She was lying sideways on the bed and clutching a pillow over her face. Her body was shuddering like she was crying, but she wasn’t making a sound.

“Are you ok?” I asked. When she didn’t answer, I made my way through the wreckage and sat down next to her. I stayed there for a few minutes until she stopped crying and looked at me from under the pillow. Her eyes were wet and red.

“I thought I told you to go away,” she said, wiping her cheeks. She didn’t seem to have the strength left to even glare at me.

“Yeah, but I heard a bomb go off and wanted to see if anyone survived.”

“Funny.” Cassie rolled over with her back toward me and curled up into a ball. “Now leave me alone.”

“So are you ok?” It felt like a dumb question, but it was the only one I could think of.

“No.”

“You want to talk or anything?”

“No.”

“Fine.” At least I’d tried. I was sure I’d find out more about it later when mom got home.

She didn’t get in until around midnight. Cassie waited up for her. I was supposed to be asleep, but I snuck out of my room and listened from the top of the stairs as they talked in the kitchen.

Apparently Cassie’s old boyfriend had gotten pissed off for some reason and started blabbing to everyone that Cassie had a dick. A guy came up behind her at lunch and grabbed her crotch to see for himself. I knew she wore an athletic supporter to hide the bulge, but if he’d gotten a good feel it would’ve been easy for him to tell what she had down there. Cassie had elbowed him in the gut, then he’d shoved her and called her a freak. Some other kids stepped in before it went any further, but the asshole and his friends had hounded her all day.

“Now everybody looks at me like I’m a mutant or something,” I heard Cassie say. “I hate this body! I hate it!” She started crying again and I heard mom trying to comfort her. I hadn’t really thought about it much before, but I realized Cassie was pretty unhappy about being different. It pissed me off those guys had messed with her like that. I wished I was older and bigger so I could do something about it.

Whatever mom said to her seemed to help though. They started heading upstairs, so I ran and got back into bed. They talked a little more in Cassie’s room and then said goodnight. I pretended to be asleep as mom came in to check on me. She sat down on the bed next to me and I felt her run her hand over my hair.

“Go easy on your sister, Bobby.’ She told me. “Things are hard for her right now.” I wondered if she knew I was awake. Probably. She always seemed to know. She kissed me goodnight and then left.

I waited until I was sure she’d gone to bed, then I got up and went down the hall. I opened the door to Cassie’s room as quietly as I could and slipped inside. I followed the sound of her soft breathing over to her bed and slid quickly in under the blanket, nestling up against her like I’d used to do when we were little. She tensed up for a second when I put my arms around her, but then relaxed again. It felt really good holding her like that. I hoped it felt nice for her too.

The next thing I knew mom was waking us up for school. She didn’t seem mad that I’d gone to sleep in my sister’s bed. If anything she seemed to think it was cute. Cassie didn’t want to go, but mom reminded her about the talk they had last night and Cassie eventually went. I felt bad for her. I’d had my share of teasing in school and I’d hated it, but what she was going through was probably a million times worse. I hoped we’d still have a house left after she got home that day.

When Cassie did get home I was surprised to see that she was in a decent mood. She wasn’t exactly happy, but she seemed more like her normal self. So normal in fact that I couldn’t resist the urge to snap her with a damp rag when we were cleaning up the kitchen. She was leaning over and her ass was just too tempting a target. The cloth impacted against her butt with a startlingly loud crack. She yelped and spun around with murder in her eyes. I ran, laughing like a maniac the whole time.

She cornered me in the living room before I could make the stairs. I tried to fake her out and jump past, but she caught me and tackled me down onto the couch. I did my best to escape, but her wet hands gave her an unfair advantage when grabbing my clothes. They also hurt when she pinned me face down with her knees in my back and started spanking me hard on the butt.

“If you’re gonna act like a brat, you’re gonna get treated like one,” she said, her voice sounding stern though I was sure that she had a huge grin on her face. It wasn’t really a typical spanking either. She rested her hand on my butt for a little while in between smacks, sometimes even squeezing it a bit. It was embarrassing and the spanking part hurt, but the more gentle stuff felt kinda good. After a minute she suddenly reached underneath me and put her hand on my crotch like she was checking to see if I was hard. And if course, I was.

“Perv.” She gave me another hard whack on the ass, then let me up and went back to the kitchen. I followed slowly, my rear end smarting and my dick hard as a rock. I watched Cassie’s butt as she walked, suddenly feeling more horny than I ever had in my life. She went back to the sink and a few seconds later I moved up from behind and grabbed her, my dick pressing against her ass. Even though I hadn’t planned it that way, my hands ended up right on her boobs. They felt warm and heavy and really nice in my palms.

I was way too turned on to listen. I caught her and put my hands back on her tits, squeezing them a little as I started rubbing against her like I’d done on her bed. I felt like I was going to cum even with our clothes still on. I kept expecting her to stop me again, but she didn’t. She just leaned forward, putting her hands on the counter as I played with her boobs and slowly humped her butt. After only a few minutes I started to cum, feeling a rush of sticky heat fill my underwear. I rested up against her for a bit, feeling her boobs moving slowly up and down in my hands as she breathed. It felt really neat.

Suddenly she turned around and pushed me down on my knees. I watched as she quickly undid her pants, her stiff cock falling out almost right away. I didn’t hesitate. I started sucking it, hearing Cassie groan softly as she flexed her hips toward my mouth. I reached around and started feeling her butt as I sucked on as much of her dick as I could. The look on her face told me that she was really enjoying it, and I started to wonder what having my own sucked would feel like. She put her hand on my head and ran her fingers roughly through my hair, then a few seconds later her cock got even harder and started squirting in my mouth. It didn’t taste as gross as I remembered, and I decided to swallow it and see what would happen. It didn’t kill me. Cassie moaned and leaned back against the countertop, and I kept sucking her gently until she pushed me away. She gave me a weird little smile as I stood up, then smacked me again on the butt.

A month went by. Cassie and I messed around a few more times but we didn’t really do anything different. Then it was my fourteenth birthday. Cassie had hinted earlier that she was going to give me something ‘special.’ Of course with her that could mean anything, so I wasn’t sure if I should be excited or afraid. I ended up forgetting about it entirely until the night of my birthday.

Everyone had gone to bed. I was almost asleep when I heard the quiet noise of someone opening my door. I rolled over on my back to look, and In the dim blue glow from my clock I could see it was Cassie. She didn’t say anything, she just sat down on the edge of the bed and pulled the covers down to my knees. I was wearing only a pair of briefs. She reached out and put her hand flat on my stomach, resting it there for a second before running it slowly down along my thigh. I didn’t know what she was planning, but the way she was touching me was quickly getting me hard. She seemed to notice and moved her hand up over my crotch, rubbing my hardon lightly through my underwear. It felt great.

Cassie tugged my briefs down and leaned over, seeming to look at my dick for a while. Then I held my breath as she suddenly grabbed my cock and lowered her head down to it, sliding it almost all the way into her mouth before she started moving her lips and sucking. Oh. My. God. It felt so warm and wet. My whole body started trembling and I felt my hips pushing up like I was trying to hump her mouth. I hadn’t imagined that anything could feel so good. It only took her a minute or so to make me cum, and all I could do was lay there and gasp as I felt my dick jump and start exploding in her mouth. Cassie slowed down but didn’t stop. I couldn’t tell if she was swallowing it or not, but she didn’t take her mouth away even after I was done. I was still so hard it almost hurt. When it was obvious that I wasn’t going soft she started blowing me again, holding my cock around the base while she rubbed my thigh with her free hand. I watched her head bob up and down, thinking how incredibly hot it was that she was sucking my dick. This time I lasted a lot longer and was able to enjoy it more. When I came in her mouth again it was over with quicker than the first time, but it felt even more intense.

Cassie let go of my cock and sat up, wiping her chin with the back of her hand. She looked at me and grinned as she smacked me lightly on the thigh.

“Happy Birthday, Knob,” she whispered.

“Thanks.” I meant it. That was easily the best present I’d ever gotten. She threw the covers back over me and left. I fell asleep almost immediately.

More time passed. I started becoming friends with a girl I knew at school. Her name was Gail and she was kind of shy and nerdy, but in a cute way. We were hanging out more and even went over to each others' houses a few times, though it still seemed like just a ‘friends’ thing. There were plenty of times when we were alone together but I was too nervous to try anything. I wasn’t sure that she wanted me to anyway.

Then Gail mentioned that her parents were taking a trip and wouldn’t be home all weekend. She seemed even shyer than usual when she asked if I’d like to come over on Friday night after they left. I think I said yes, though my pulse was suddenly pounding so hard that it drowned everything out. My imagination was racing all week long as I wondered what she had in mind. I wasn’t really expecting to get in her pants or anything. Despite what had already happened with Cassie I would’ve been happy just making out with a girl, even though I was worried I’d mess it up somehow.

By Friday afternoon I was so nervous I could barely keep still. I was sitting on my bed watching the clock when a sudden sound from my doorway make me jump. It was Cassie, standing there with a smirk on her face.

“Lemme guess,” she said, “you’re sneaking over to your girlfriend’s house tonight.” My sister leaned up against the door and crossed her arms, the teasing grin never leaving her face. “Want me to buy you some condoms? Lube maybe?”

“Well fine,” she said, straighening up and turning to leave. “I *was* going to offer you some advice, but if you’re just gonna be a little douche, forget it.”

I sat there for a few minutes as I fought a painful battle with my ego. When it finally surrendered, I got up and went to Cassie’s room where she was busy folding clothes.

“What advice?” I asked, hoping she wasn’t just messing with my head.

“Oh nothing. I forgot you’re fourteen now. I’m sure you know everything there is to know about girls.”

I bit my tongue before I could say something stupid, like how she wasn’t exactly an absolute expert on girls either, what with her cock and all. “Hey, I know plenty. I just don’t wanna do anything that’ll gross her out. If something does happen, I mean.” I hesitated, feeling lame. “I haven’t exactly made out with a lot of girls or anything.”

Cassie looked at me. “You ever even kiss before?”

I stared at the floor, embarrased.

“Don’t sweat it, Knob. Its not hard. Just do it like they do in the movies.” I looked up and saw a wicked grin slowly spreading over her face. “Help me fold these and maybe I’ll show you a few things.”

I helped. When everything was folded neatly and put away, Cassie sat on the bed and motioned me to sit down next to her. I sat down, wondering exactly what it was that she planned to show me.

“Okay, the main thing is to start off slow.” She said, moving in and pulling my arm around her shoulders. “Don’t get too grabby and stuff, that’ll freak her out. Just get close and the rest kinda takes care of itself.”

I slid myself over further until her body was pressed snugly against mine, my hand resting on her upper arm. She smelled good. Cassie lifted her face up toward me and closed her eyes, her lips only inches away. I wasn’t sure how far she wanted to take this, but the opportunity was definitely there.

“This is the part where you kiss her, dumbass,” she said quietly.

I leaned in toward her, keeping my eyes open to watch her reaction as I touched my mouth to hers. Her lips felt incredibly soft and warm. She didn’t respond right away, but after a few seconds she started kissing me back. After a minute or so she opened her mouth and I felt her tongue pushing against my lips. I let it in and started chasing it with mine, my dick getting hard almost instantly. Kisses like that had always seemed gross when I saw other people doing it, but my opinion was quickly changing now that it was happening to me.

Cassie was slowly edging herself into my lap as our kissing got hotter. I pulled her closer against me, feeling her tits pressing firmly against my chest. She only kissed me harder and slid her hands around my waist.

It suddenly occurred to me that I was making out with my own sister. My response to that was to slide my hands down and grab her ass firmly with both hands. Cassie moaned and started sucking on my bottom lip. I got the feeling that she wasn’t playing around. I wasn’t exactly sure what was happening here, but I did know that I liked it.

After a few more minutes I let go of her ass and moved my hands up front. She moaned again as I palmed her boobs. I squeezed them and she started grinding herself slowly against my lap. I could feel the bulge of her hardon rubbing up against mine, and for some reason that made me hornier than ever. I broke the kiss and lowered her down onto the bed. I’d seen this part in movies before too, the part where they get naked and fuck like crazy.

Straddling her, I grabbed the hem of her shirt and pulled it up. She surprised me a little by raising her arms and helping me take it off. With that out of the way, I reached under her back with the intent of taking her bra off too, but I couldn’t seem to unhook it for the life of me. Finally Cassie did it, and the second it came loose I caught her naked boobs in my hands and gave them a firm squeeze. It was my first time feeling them without her bra in the way, and they felt great. Warm and soft and firm all at the same time. I leaned in and kissed her again, feeling her nipples getting harder each time they brushed against my fingers. I suddenly wondered what they’d feel like in my mouth, and I decided to find out. I moved from sucking on Cassie’s tongue to sucking on one of her nipples. She gasped and moaned softly as I switched back and forth from one to the other. She seemed to really like what I was doing, but I was too damn horny to concentrate on it for long.

I undid her jeans and pulled them off. Her boxers joined them on the floor a few seconds later. I was a little surprised that she wasn’t trying to stop me. Cassie usually liked to make things difficult, but this time she was just laying there with her eyes closed. Naked. I’d never seen her fully naked before, and I had to stop for a minute just to take it all in. Her big firm boobs were rising and falling quickly with her breathing. I moved my eyes down her flat stomach and over the wide curves of her hips. Her dick was stiff and sticking almost straight up. I ran my hands slowly up and down over her smooth legs, suddenly at a loss for what to do next. She was so sexy that I wanted to touch all of her at once. I also had an incredibly strong urge to fuck her, but I couldn’t. So I did the only thing I could think of. I turned her over and undid my pants. I slid them down and off, then lay on top of her with my body pressed firmly down on hers. My dick nestled right up between the firm cheeks of her ass like it belonged there. Her naked skin felt awesome underneath me as I started humping against her butt.

Cassie was moving too, grinding her big ass up at me in little circles. It felt great, but I still wanted more. Then I got an idea. I gathered up a bunch of my spit and rubbed it over both my dick and the cleft of her ass. When I started moving again, the slipperyness felt much better. After a minute I decided to try something different. I took hold of my dick and started rubbing it up and down firmly over the length of her crack, sometimes poking it in to see what she’d do. She didn’t say anything, though she was breathing really fast and heavy. I applied a little more pressure, really liking how it felt to have the head of my dick wedged firmly between her cheeks.

Suddenly, I felt a sensation like something pushing back against the tip of my cock. I eased off a little and then pressed in again. Cassie groaned softly and something seemed to nip at the head of my dick. It took me a second to realize what it was. Her butthole. I froze for a moment. I knew that you could have sex that way too, but it was something I never imagined myself doing. A weird thrill shot through me, and I just had to see what would happen if I pushed a little more. She groaned again and I felt the pressure against the head of my cock increase.

I jumped up and went to her dresser. Sure enough, there was a tube of vaseline in there. It was actually some kid of lotion, but it was good enough for me. My hands were shaking a little as I squirted some out and rubbed it all over my dick. I rubbed some more into the crack of her butt and quickly got back on top of her. I found the spot again and pushed slowly, this time feeling the pressure slowly spread around the head of my dick. It was going in. Then she clamped down on me and I almost came right there. After a second she relaxed again, and I felt my cock pushing a little deeper inside. It felt completely awesome. Her butthole kept clenching at my dick like it didn’t want it there. Cassie was gasping and digging her fingers into the sheets. For a second I wondered if it hurt, but then I felt my pubic bone come to rest against the soft skin of her butt and realized that I was all the way inside. Balls deep in her ass.

Instinct took over, and I grabbed her by the shoulders and started fucking her. It was so intense that I forgot about being gentle or anything else, the only thought in my head was the feeling of her butt squeezing down around my cock. Cassie squealed and squirmed underneath me, her voice alternating from low grunts to high-pitched squeaks. She might have been trying to push me off her, but by then I was too far gone. I felt her ass grabbing at my dick and her body shuddering underneath me, and with a final thrust I pushed in deep and started cumming harder than I ever had before in my life.

I shuddered, my cock jerking spastically in the tight grip of her butt. As the last pulses faded I fell limp on top of her body, my head spinning. She was panting and groaning softly, the muscles in her ass still trying to push me out. I started feeling guilty at how I’d lost control and pulled out of her as gingerly as I could. I checked my dick, feeling relieved when I didn’t find any blood or poop on it. I wiped it off with my underwear and sat down next to my sister. She hadn’t moved much. I wondered if she was ok. I started rubbing her back a little, hoping she wouldn’t hate me. After a few seconds she suddenly rolled over and punched me hard on the arm.

“Ow,“ I replied.

“Well that’s what you get. That hurt!”

“Sorry.” Looking more closely, I saw that the sheet underneath her and the middle of her stomach were all wet with cum. There was lot of it, and it sure wasn’t mine. “Doesn’t seem like it hurt *too* bad though.”

She realized what I was looking at and punched me again, but not as hard this time. She got up and grabbed a towel, seeming embarrassed as she wrapped it around herself and headed for the bathroom. I gathered up my clothes and left, still dazed by what just happened. I had another hour left before I was supposed to go over to Gail’s, but I definitely wasn’t feeling nervous anymore. When Cassie was done in the bathroom I went in to take a shower. A minute later she opened the door and poked her head in.

“Just don’t expect all your dates to go like that, Knob. You’re not even close to being that smooth.” She left before I could think of a witty response. Anyway she was probably right.

After my shower I went back to my room and got ready. I was still looking forward to seeing Gail, but I was nowhere near as excited as I’d been earlier. I’d just had sex with my sister. Real sex. In the butt. Anything else that happened that day was bound to be a letdown.

Although peaking in popularity after countless /b/ posts, the origins of MSIAD remained generally unknown. Internet historians as of recent have had no success in locating the original author or posting, although documentation of the tale dates back as far as 2007.

On a relatively unheard of, borderline fetishism forum titled "getDare", some shut-in named "Hoodison" reposted the story and claimed it as his own, despite it already being a staple of *chan copypasta-culture, and furthermore his failure to actually post the entire damn story. After the ignorant sick-fucks of "getDare" praised the bastard for his "amazing original work", he claimed the story was no more than a Gary Stu fantasy, despite, once more, it not being his.

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Its a story about a dude (me - but fiction, remember), that has a sister, who happens to have a cock.